This is a renewal of the Pediatric ACTG unit for the Los Angeles area. The LAPAC consists of 6 clinical sites (UCLA, Children's Hospital of LA- pediatric and adolescent unit, Harbor-UCLA, Long Beach Memorial, Cedars-Sinai Medical Center and Children's Hospital of Orange County). This consortium has successfully worked together for the past 13 years and we have added CHOC as a new site and also an adolescent unit at Children's Hospital in 1999. We have enrolled a significant number of HIV infected women, children and adolescents representing ethnic minorities and other disenfranchised populations into ACTG trials (n=602). UCLA is the main administrative data entry, coordinating, and laboratory site with a well-integrated network and infrastructure at our sub sites. We have established effective liaisons with an LA County surveillance study, community health centers for HIV screening of pregnant women, a countywide social service network for HIV+ children, community representatives and a pediatric Community Advisory Board. All centers provide primary care for HIV infected children and adolescents and three are also designated perinatal centers, which can enroll HIV+ pregnant women into clinical trials with liaisons for continued care and access to clinical trials. This consortium provides clinical care for 80% of the HIV exposed or infected children in LA (n=483) and is a catchment area for 75,000 of the deliveries. This unit has made major scientific contributions both in the design and implementation of the overall pediatric/perinatal scientific agenda including studies to enhance the knowledge of pathogenesis and to significantly reduce perinatal transmission to develop new methods of early diagnosis in infected infants, to provide insight into the factors associated with disease progression in infants and children and to advancing the science, providing leadership and also contributing to the productivity of the national pediatric effort. The applicants plan to enroll, a minimum of 60 patients/yr into clinical trials with an emphasis on perinatal and phase I/II studies and adolescents and to follow 114 continuing patients. We also plan to enroll 20-25 new HIV infected pregnant women and/or newborns, and 40 HIV infected children or adolescents into primary therapy and IBT or studies of complications. The goals are integrated into the scientific agenda and include the reduction of perinatal transmission, early treatment of infants and adolescents during primary infection and the evaluation of new potent combination therapies to enhance and prolong the lives of children/adolescents already infected with HIV. We propose to enhance outreach efforts in order to identify HIV + pregnant women and adolescents for entrance into clinical trials. The core and developmental laboratories in both virology and immunology have the capability to provide new innovative assays to enhance the overall scientific agenda and support the clinical trials.